Radiation image recording device

ABSTRACT

Disclosed is a radiation image recording device comprising a source of radiation and a radiation receiver which are movable in a vertical direction in order to be positioned relative to a standing patient, and an image processing device for creating an output image based on the recorded image data. The source of radiation and the radiation receiver are movable in a controlled manner into successive image recording positions via a control device so as to record an area of analysis which exceeds the height of the active area of the digital radiation receiver, one radiation image being recorded in each image recording position. The positions are defined in such a way that the recorded radiation images cover the area of analysis while the image processing device is embodied so as to create a full image representing the entire area of analysis based on the image data of the individual radiation images.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to the German application No.10244609.1, filed Sep. 25, 2002 and to the International Application No.PCT/DE03/03138, filed Sep. 22, 2003 which are incorporated by referenceherein in their entirety.

FIELD OF INVENTION

The invention relates to a radiation imaging device with a radiationsource and a radiation receiver, which can be moved in a verticaldirection to be positioned in relation to a standing patient, and withan image processing device for producing an image that can be outputbased on the recorded image data.

BACKGROUND OF INVENTION

In modern X-ray-based diagnostics it is increasingly frequentlynecessary to examine large examination areas, e.g. the entire spinalcolumn or the leg area to diagnose bone positions. The patient is herebyscanned in a standing position with the radiation imaging device, i.e. aconventional X-ray device comprising an X-ray tube and an X-rayradiation receiver. The receiver generally has a 40×120 cm filmcassette, if this is large enough to map the whole examination area. Asan alternative it is known that smaller film cassettes can be used torecord a plurality of storage plate images, which map the examinationarea, and these can then be stuck together to give an overall image.This process is elaborate and complex and the storage plates requiresubsequent development, which takes a relatively long time, so diagnosiscan not take place at the same time as recording.

DE 42 31 583 A1 discloses an angiographic X-ray diagnostics device, withwhich a plurality of individual images are produced of a prone patientby incremental displacement. The individual images are stored in animage storage unit of a laser image reproduction device, display linesbeing omitted from the edges of the images so that an image of theentire examination area can be printed out on the laser imagereproduction device without overlap.

SUMMARY OF INVENTION

An object of the invention is therefore to specify an improved radiationimaging device.

To achieve this object according to the invention, with a radiationimage recording of the type mentioned above comprising a digitalradiation receiver, i.e. a known semiconductor flat detector, to recordan examination area exceeding the height of the active area of theradiation receiver, the radiation source and radiation receiver can bemoved in a controlled manner into successive imaging positions by meansof a control device, a radiation image being recorded in each of thesepositions, the positions being defined such that the recorded radiationimages cover the examination area and the image processing device beingconfigured to produce an overall image representing the entireexamination area based on the image data of the individual radiationimages.

The invention advantageously proposes incremental scanning of theexamination area, a radiation image being recorded in every definedimaging position. A central control device controls the radiation sourceand radiation receiver into the respectively defined position and oncethe image has been recorded, it is read from the radiation receiver andsent to the image processing device. When the entire examination areahas been scanned by recording a plurality of images, the overall imagerepresenting the entire examination area is produced by computation inthe image processing device based on the data of the individualradiation images. This overall image can then be output and thediagnosis made.

Compared with the prior art the radiation imaging device according tothe invention has a number of advantages. On the one hand the overallimage is produced very quickly, as, if its design is adequate, the imageprocessing device can compute the overall image immediately after thelast individual image is produced. Diagnosis can therefore take placealmost immediately after the last individual image has been recorded.Also the image processing device advantageously produces a singleoverall image, which can be output immediately after its production.There is therefore no longer any need for complex or time-consumingdevelopment or for the additional process of sticking individual imagestogether after development. A further important advantage is that thisoverall image can be archived without further ado in a suitable patientdata management unit, which can be achieved in a significantly simplermanner by storage on a suitable data medium than the hitherto standardarchiving of storage plate images.

A further important advantage is that the device used to implement therecording technique defined above can be a standard thorax or skeletonrecording device, which does not have to be modified very much for thispurpose, except primarily in respect of the image processing device,which must be designed accordingly.

Generally the radiation imaging device according to the invention allowsthe fast and uncomplicated and immediately informative production of anoverall image of a large examination area, which is significantly largerthan the active area of the radiation receiver.

In a development of the invention, the control device can be configuredfor the automatic determination of the respective positions based on theheight of the examination area and the height of the active area of theradiation detector. Before the image is actually recorded, the doctortherefore determines which examination area is to be scanned. In theexample the left leg is to be examined from the heel to the neck of thefemur. The doctor inputs said patient parameters into the controldevice, which then uses the known active area of the radiation detector,i.e. the detector area used actively for imaging, where X-ray radiationis converted to image data, to compute the position to which theradiation source and radiation receiver must automatically be moved.This procedure is possible both when the active area of the radiationdetector is not variable and with detectors with a variable active area,i.e. with which the doctor can select a specific detector range, to usefor the actual imaging process. As set out above, this area is known tothe control device, as is therefore the height of the area in relationto the vertical movement, so that the relevant recording positions canbe automatically determined and automatically assumed without furtherado.

The radiation source and radiation receiver are thereby expedientlymoved synchronously, i.e. they are moved from one position to the nextat the same time. Of course operation with asynchronous movement is alsorequired, with first one and then the other component being moved.Movement always takes place symmetrically, i.e. always by the samedistance, so that with the type of recording, in which a standingpatient is scanned, the radiation source and radiation receiver arealways opposite each other in a horizontal plane, thus they are alwaysin the same plane.

Movement from one recording position to the next and imaging in therespective recording position advantageously take place automatically.Therefore when imaging starts, once the individual recording positionshave been determined, the control device moves the radiation source andradiation receiver, which is for example as 40×40 cm image receiver,from an initial position, to which both components are always moved asthe basic position, to the first recording position. When this has beendone imaging takes place automatically and when the recorded individualimage has been read, both are moved to the next recording position,where recording again takes place, etc. This process continues until thelast image has been recorded, whereupon both components are for examplemoved back to the initial position. In parallel with this the imageprocessing device immediately starts to process the individual imagedata to produce the overall image. This also expediently takes placeautomatically, so that after activating the start button the doctorreally has nothing more to do until the final image is output.

As described, the image processing device is configured such that ituses the individual images to produce an overall image that shows theentire examination area precisely mapped and with exact resolution fordiagnostic purposes. It must also be able to position two adjacentimages of the examination area in relation to each other and join themsuch that there are no edges or misalignments and the examination area,e.g. the lower leg, is mapped precisely in respect of the recordedstructure. To this end it is expedient according to a first embodimentof the invention for the positions in which the recordings are made tobe defined such that two successively recorded images overlap at theedges. Therefore two successively recorded images show the samestructures at the edges, on the basis of which the image processingdevice, e.g. using suitable edge detection algorithms or similaralgorithms, which detect the commonalities in the images, can determinethe precise alignment of the two images in respect of each other andsuperimpose them exactly. Of course this is done so that no edges,brightness differences, etc. caused by the superimposition are visiblein the overall image produced. The superimposition should thereby not betoo large; a superimposition of for example 3–5 cm is possible based ona 40×40 cm image receiver. Sufficient structural commonalities arealready present in such a relatively narrow area to allow exactalignment and overlapping of both images on the part of the imageprocessing device.

In an alternative embodiment of the invention the positions are definedsuch that two successively recorded images are essentially adjacent toeach other. The overlap here is therefore only a few millimeters.Production of the overall image here depends primarily on the one handon the fact that the radiation source and radiation receiver can bemoved exactly into the predefined positions and on the other hand thatthe patient does not move during the process. Both images are almostdirectly adjacent to each other. Here too of course the imagingprocessing device can carry out an analysis of the edge area in respectof corresponding structures, in so far as some occur in the fewmillimeters of overlap. As an alternative to analyzing the two edgeareas, it is also possible to use suitable algorithms to search forcontinuing structures in the first and second images. While for examplethe edges of a bone are detected in the first recorded image, theseedges are also determined in the next recorded image and both images arepositioned in respect of each other such that the edges coincide or areprecise continuations of each other.

The overall image can either be exposed onto a film if necessary in areduced format as a hard copy, e.g. written onto a storage plate, or canbe output on a monitor. Outputting on a monitor is of course essentialfor fast diagnosis. The overall image can thereby be output on themonitor in the recorded format or in a larger format. As the monitor isof course smaller than the recorded examination area, the clearly largeroverall image is viewed simply by moving the overall image on themonitor, which can be done by scrolling. It is if course also possibleto display the overall image in an enlarged format compared with theactual recorded format, so that some structures can be displayed evenlarger.

The radiation source and radiation receiver are expediently arranged on,if necessary telescopic, ceiling or floor gantries, which allow simpleautomatic movement. A suitable mechanical system is provided for thispurpose, which in particular allows exact positioning of both componentsin the respectively defined recording position, in order to be able torecord the individual images, as defined beforehand by means of thecontrol device.

For structural reasons the radiation receiver, i.e. the solid statedetector, in particular cannot be moved to just above the floor, i.e.the active area is always a certain distance above the ground. For legimaging it is however necessary for the heel bone at least to be mapped.To resolve this, according to the invention a platform is provided tohold the patient with retaining devices for the patient. This platform,on which the patient has to stand, compensates for this misalignment dueto the structure, so that the heel bone is also recorded without furtherado. The retaining devices are provided so that the patient stands firmand without movement, as said patient cannot change position while theplurality of individual images are being recorded.

The retaining devices can thereby be configured as handles, the heightof which can be varied, so that people of differing heights can besecured optimally. It is also possible to design the retaining means ascorresponding straps, etc., which are used to belt the patient firmly inposition.

A radiation-transparent plate is also expediently provided on theplatform on the side facing the radiation receiver, to prevent thepatient coming into contact with the radiation receiver.

BRIEF DESCRIPTION OF THE DRAWINGS

Further advantages, features and details of the invention will emergefrom the exemplary embodiment described below and with reference to thedrawings, in which:

FIG. 1 shows a schematic sketch of a radiation imaging device accordingto the invention, and

FIG. 2 shows a schematic sketch showing the “fusion” of three individualimages to produce an overall image.

DETAILED DESCRIPTION OF INVENTION

FIG. 1 shows a radiation imaging device 1 according to the invention,comprising a radiation source 2, in this case an X-ray emitter, and aradiation receiver 3, in this case a digital solid state detector. Theradiation source 2 is arranged on a gantry 4 with a telescopic bar 5 andcan therefore be moved vertically as shown by the double arrow A. Thesame applies to the radiation receiver 3. This is also arranged on agantry 6 and can also be moved vertically, as shown by the double arrowB. While the gantry 4 is supported on the ceiling, the gantry 6 is afloor gantry.

A platform 7 is provided in the vicinity of the radiation receiver, onwhich the patient P has to stand for the recording. Retaining means 8 inthe form of vertically movable handles (see double arrow C) are arrangedon both sides of the platform 7, which the patient can hold on to, assaid patient has to stand still during imaging. A radiation-transparentplate 9 is also provided at the back, arranged there for protectionpurposes to prevent the patient coming into contact with the radiationreceiver 3.

The radiation imaging device according to the invention also comprises acentral control device 10, to which an imaging processing device 11 anda monitor 12 are assigned. The control device 10 is used to control thevertical displacement of the radiation source 2 and the radiationreceiver 3 exactly so that different recording positions can be assumedand to control the imaging operation. The image processing device 11 isused to compute an overall image from the recorded individual images,which is then recorded on the monitor 12.

In the exemplary embodiment shown the right leg of the patient P is tobe recorded and output as an overall image for the doctor. To this end,the doctor uses a suitable input means (e.g. a keyboard, etc. not shownin more detail here) to input the geometric data of the examinationarea, in this case the right leg, into the control device 10. The doctormust define the extent of the examination area in relation to thevertical. In this instance the examination area is clearly larger thanthe active area of the radiation receiver 3. To be able to map itexactly in an overall image, it is necessary to produce a plurality ofindividual images in different recording positions, in order to be ableto compute an overall image therefrom. When the vertical position andlength of the examination area have been defined, the control device 10computes the positions to which the radiation source 2 and radiationreceiver 3 must be moved, in order to record individual images of theexamination area, which map this as a whole. This can be done by thecontrol device 10 without further ado, as it knows the examination areaexactly and is able to locate it based on the corresponding data inputby the doctor and it also knows the active area of the radiationreceiver 3, i.e. the area in which the image data mapping theexamination area is actually generated. The respective recordingpositions, into which the radiation source 2 and radiation receiver 3have to be moved to image the examination area, can be determined fromthese without further ado. In the exemplary embodiment shown there arethree recording positions. Starting from the lowest recording positionI, to which the control device moves the radiation source and radiationreceiver, from an initial position (not shown), a first image isrecorded there, showing the leg of the patient from the heel bone tobelow the knee for example. After successful recording, which is alsocontrolled via the control device 10, the image data of this first imageis read out and sent to the image processing device 11. The radiationsource 2 and radiation receiver 3 are then moved to the recordingposition II, the positions being determined exactly in each instanceusing suitable position detection means. Once they arrive there, asecond individual image is recorded, showing the leg of the patientbelow the knee to the center of the thigh. After successful recordingand reading of the image data, a third movement takes place to the thirdrecording position III, where a third image is recorded on arrival,showing the examination area from the center of the thigh to the hip.When this image has been recorded, it too is read out and sent to theimage processing device 11, in which there are then three individualimages. These three individual images are then used to produce anoverall image by computation, which is then output on the monitor 12.

The recording positions are thereby defined such that for example twosuccessively recorded individual images overlap by a certain distance.Based on an approx. 40×40 cm image receiver, the active area of which istherefore 40×40 cm for example, the overlap can be 3 or 5 cm forexample. This is expedient so that the image processing device 11 canuse suitable algorithms to detect coincident areas in two successivelyrecorded images and can thus position the images exactly in relation toeach other, to give a uniform overall image without edges and brightnessdifferences, etc. Alternatively the recording positions can also beselected so that the images connect together almost seamlessly, theimage processing device 11 then using suitable algorithms to search forcontinuing structures in two successively recorded images, in order tobe able to align both images in relation to each other.

In each case the entire operation is carried out automatically via thecontrol device 10. If said control device 10 knows the parametersmentioned above relating to the examination area, the recordingpositions are determined automatically depending on which imageprocessing mode (i.e. with edge overlap or directly adjacent) has beenselected, by the doctor for example. Once this is all defined, thedoctor only has to press the start button on the control device 10,whereupon the entire imaging, displacement and image evaluation processoperates automatically.

As an alternative to inputting any parameters relating to theexamination area, it is of course also possible for the doctor to definethe examination area by moving the radiation detector to a firstposition and a second position, which approximately define the positionsfor the first and last recorded images. The examination area is thus asif defined directly in the coordinates system of the movement trackingsystem of the radiation receiver. Based on these two positions, therespective intermediate recording positions can then be determined. Itis thereby possible of course that the overall length of the examinationarea is not precisely a multiple of the height of the active area of thereceiver, taking into account any overlaps. It is therefore possible forthis purpose to use corresponding diaphragms at the radiation sourceduring the last recording just to radiate a sub-area, etc. Thusdifferent variations are possible for defining the position and lengthof the examination area.

FIG. 2 is in the form of a schematic sketch showing how three individualimages are used to produce an overall image. In the example shown threeindividual images B1, B2 and B3 were recorded.

The individual image B1 was recorded first, showing the majority of thelower leg to just below the knee. The individual image B2 is thenrecorded, showing the knee and some of the thigh. Finally the individualimage B3 is recorded, showing the remainder of the thigh with the neckof the femur.

For simple arrangement of the images in relation to each other, theimages were recorded so that they overlap partially. Each image containsan area of overlap with the previously recorded image, in other words anarea in which the recorded structure is coincident to this extent. Inthe image B1 this is the upper narrow edge area Ü1. Individual image B2also has the area of overlap Ü1 at its lower edge with an area ofoverlap Ü2 at its upper edge, which is repeated in the same way in thenext recorded individual image B3. The imaging processing device 11 isnow able to use these areas of overlap to align two successive imagesexactly in respect of each other using suitable analysis algorithms andoverlap these in the region of the areas of overlap, thus producing anoverall image G, which shows the entire examination area from the footto the neck of the femur. Image fusion is thereby such that there are noedges or brightness differences, etc. in the region of the transitionsfrom one individual image to another.

The overall image thus produced is now expediently output on the monitor12. As the image area of said monitor is smaller than the overall imageG, which expediently shows the examination area 1:1, only part of theoverall image G can be displayed on the monitor 12. A suitable scrollingdevice can now be used to move the image on the monitor 12 withoutfurther ado, as shown by the double arrow D.

As well as displaying the digital overall image B on the monitor, it isalso possible without further ado to archive said image and store it ona data medium, in the example shown here a CD-ROM 13. Given the enormousamount of storage space on such a data medium, a plurality of furtheroverall images can of course also be stored there (as can individualimages of course), thereby allowing significantly more expedient andconvenient archiving than when the storage plates used in the prior arthad to be stored.

1. A medical imaging device, comprising: a radiation source; a digitalradiation detector for recording images, the radiation source and thedigital radiation detector configured to be moved vertically relative toa patient in a standing position; a control device adapted to move theradiation source and the digital radiation detector to a plurality ofsuccessive imaging positions for recording an image of an examinationarea having a height exceeding a height of an active surface area of thedigital radiation detector; and an image processing device forgenerating a combined image showing the examination area, wherein theplurality of successive imaging positions are calculated by the controldevice based on user input data providing the height of the examinationarea and based on the height of the active surface area of the digitalradiation detector, an image is recorded at each imaging position, theimages recorded at the imaging positions in their entirety covering theexamination area, and the image processing device is configured togenerate the combined image using the images recorded at the imagingpositions.
 2. The medical imaging device according to claim 1, whereinthe control device is adapted to move the radiation source and thedigital radiation detector synchronously.
 3. The medical imaging deviceaccording to claim 1, wherein the control device is further adapted tomove the radiation source and the digital radiation detector to theimaging positions successively using an automation program.
 4. Themedical imaging device according to claims 1, wherein the imagesrecorded at adjacent imaging positions overlap in an overlap area. 5.The medical imaging device according to claim 1, wherein the imagesrecorded at adjacent imaging positions overlap a few millimeters at edgeareas of the respective adjacent images.
 6. The medical imaging deviceaccording to claim 4, wherein the imaging processing device is furtheradapted to arrange the images recorded at the adjacent imaging positionsrelative to the combined image using the overlap area.
 7. The medicalimaging device according to claim 5, wherein the imaging processingdevice is further adapted to arrange the images recorded at the adjacentimaging positions relative to the combined image using algorithms tosearch for continuing structures in the respective adjacent images andto position the respective adjacent images in respect of each other suchthat edges of the continuing structures in the respective adjacentimages coincide or are precise continuations of each other.
 8. Themedical imaging device according to claims 1, wherein the combined imageis displayed on a monitor or printed on a hardcopy.
 9. The medicalimaging device according to claim 8, wherein the displayed or printedcombined image is scaled down.
 10. The medical imaging device accordingto claim 1, wherein the combined image is displayed on a monitor using adisplay format corresponding to a recording format of the combinedimage, the combined image movable on the monitor using a scrollingmechanism.
 11. The medical imaging device according to claim 1, whereinthe combined image is displayed on a monitor using a display formatexceeding the original size of the examination area, the combined imagemovable on the monitor using a scrolling mechanism.
 12. The medicalimaging device according to claim 1, wherein the radiation source andthe digital radiation detector are arranged on adjustable wall- orfloor-mounted supports.
 13. The medical imaging device according toclaim 12, wherein the supports are telescopic supports.
 14. The medicalimaging device according to claim 1, further comprising a platform foraccommodating the patient, the platform having a safeguard device forsecuring the patient's standing position.
 15. The medical imaging deviceaccording to claim 14, wherein the safeguard device includes a handhold.16. The medical imaging device according to claim 14, further comprisinga plate permeable for radiation emitted by the radiation source, theplate arranged on the platform and facing the digital radiationdetector.
 17. The medical imaging device according to claim 1, whereinthe user input data is provided by input means to input the geometricdata, including the height, of the examination area.
 18. The medicalimaging device according to claim 1, wherein the user input data isprovided by movement of the radiation detector to a first position andto a second position to define a first and a last image of the pluralityof successive imaging positions.